Started out intending to follow a pattern, but this has morphed. With 2 strands of yarn, I CO 64 sts in the round and worked stockinette until it was about 18” long, then BO using 3-needle BO to seal the end. Then I picked up sts on the wrong side all around, picking up both sides on the other end, closing the tube so the base is super-soft-and-squooshy. Then I knit stockinette all around (from the wrong side) for about 8” and looped it around to form an edge, stuffed it with polyfill and backstitched it onto the bottom edge to seal it up. So the base is stockinette and the edge is the purl side for contrast.

Lessons learned:
Knit the round edge with smaller needles so it doesn’t stretch out as much (polyfill shows a bit).